The present invention relates to compounds, compositions and methods for preventing and treating viral infections, and the diseases associated therewith, particularly those viral infections and associated diseases caused by viruses of the Pneumovirinae subfamily of the Paramyxoviridae.
The Pneumovirinae subfamily of the Paramyxoviridae family consists of pneumoviruses that cause significant disease in humans and a number of animal species including cattle, goats, sheep, mice and in avian species.
Human respiratory syncytial virus (RSV), the prototypic member of the pneumovirus group, is the major pediatric viral respiratory tract pathogen, causing pneumonia and bronchiolitis in infants and young children. RSV disease is seasonal, with outbreaks in the U.S. typically beginning in November and continuing through April. During these yearly epidemics, approximately 250,000 infants contract RSV pneumonia, and up to 35% are hospitalized. Of those hospitalized, mortality rates of up to 5% have been reported. Children with underlying conditions such as prematurity, congenital heart disease, bronchopulmonary dysplasia and various congenital or acquired immunodeficiency syndromes are at greatest risk of serious RSV morbidity and mortality. In adults, RSV usually causes upper respiratory tract manifestations but can also cause lower respiratory tract disease, especially in the elderly and in immunocompromised persons. Infection in elderly and immunocompromised persons can be associated with high death rates. Natural infection with RSV fails to provide full protective immunity. Consequently, RSV causes repeated symptomatic infections throughout life.
The pneumoviruses of animals and avian species are similar to the human virus antigenically, in polypeptide composition and in disease causation.
Attempts to develop vaccines for RSV are ongoing, but none have yet been demonstrated to be safe and efficacious. Vaccine development has been shadowed by adverse reactions exhibited by the initial formalin-inactivated RSV vaccine introduced in the late 1960s. Immunized children showed an increased incidence of RSV lower respiratory tract disease and developed abnormally severe illnesses, including death.
Chemotherapy with ribavirin [1-beta-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide], an antiviral nucleoside which is the only pharmaceutical approved by the U.S. Food and Drug Administration (FDA) for treatment of RSV disease, is considered only for certain RSV patients (e.g., those at high risk for severe complications or who are seriously ill with this infection). However, its efficacy and value are controversial. Recent studies have reported a failure to demonstrate either clinical or economic benefit to patients of ribavirin treatment. Moreover, ribavirin has certain toxic side-effects and, in order to minimize these, must be administred by inhalation as an aerosol in an enclosed environment.
A human intravenous immune globulin (IVIG) preparation is licensed for prophylactic use in certain patients at high-risk for RSV disease. Administration of this drug requires intravenous infusion of a large volume over a 2 to 4 hour period in children who have limited venous access due to prior intensive therapy, as well as compromised cardiopulmonary function. Moreover, intravenous infusion necessitates monthly hospital visits during the RSV season, which in turn places children at risk of nosocomial infections.
Thus, a need exists for new anti-viral agents and treatments for RSV infection that overcome the shortcomings of existing pharmaceutical preparations.
In one aspect, the invention provides a compound of the formula: 
wherein Het represents an unsubstituted or substituted five to seven membered heterocyclic ring containing one to three heteroatoms selected from nitrogen, oxygen or sulfur, said heterocyclic ring substituents being at least one selected from those consisting of hydrogen, alkyl, amino, monoalkylamino or dialkylamino;
R1 represents a radical selected from the group consisting of hydrogen; halogen; perfluoroalkyl; alkoxyalkyl; amino; alkylamino; dialkylamino; amido; alkylaminoalkyl; an unsubstituted or substituted, saturated or unsaturated, straight- or branched-chain alkyl radical, said alkyl chain substituent being at least one hydroxy group; carboxy; an unsubstituted or substituted phenyl radical (C6H5), said phenyl radical substituent being at least one selected from the group consisting of hydroxy, alkoxy, alkoxyalkyl, halogen, perfluoroalkyl, thio, nitro, carboxy, carboxyalkyl, carbalkoxy, carbalkoxyalkyl, carboxamide, carboxamidoalkyl, alkyl, cycloalkyl, alkylthio, alkylsulfinyl, alkylsulfonyl, sulfonamide, amidino, cyano, amino, amido, alkylamino, dialkylamino, alkylaminoalkyl, or alkoxy monosubstituted with a substituent selected from the group consisting of carboxy, amino, alkylamino or dialkylamino; a cycloalkyl radical; or a heterocyclic radical selected from the group consisting of pyridine, thiophene, oxazole, oxadiazole, thiadiazole, pyrazole, tetrazole, furan, pyrrole, isoxazole, imidazole, triazole and thiazole, including all positional isomers of said heterocyclic radicals;
R2 represents a radical selected from the group consisting of hydrogen, hydroxy, thio, alkoxy, carboxy, carboxyalkyl, amino, alkylamino, dialkylamino, carboxamide, carboxamidoalkyl, sulfonamide acetamido;
X represents a valence bond or a divalent linking moiety selected from the group consisting of xe2x80x94Nxe2x95x90CHxe2x80x94, xe2x80x94CHxe2x95x90Nxe2x80x94, xe2x80x94(CH2)nxe2x80x94NHxe2x80x94, xe2x80x94NHxe2x80x94(CH2)nxe2x80x94, xe2x80x94(CH2)nxe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94or xe2x80x94Nxe2x95x90Nxe2x80x94, n being an integer from 1 to 8;
Z represents a substituent selected from the group consisting of hydrogen, formyl, hydroxy or xe2x80x94Xxe2x80x94Het, wherein X and Het are as previously defined; the isomeric forms of said compound and the pharmaceutically acceptable salts of said compound.
Particularly preferred are compounds having the formula: 
wherein X is a divalent linking moiety selected from the group of xe2x80x94Nxe2x95x90Cxe2x80x94 or xe2x80x94CHxe2x95x90CHxe2x80x94; R is a radical selected from the group of hydrogen, hydroxy, alkoxy, alkyl, halogen, nitro or alkoxy monosubstituted with a substituent selected from carboxy, amino, monoalkylamino, dialkylamino or acetamido; R2 is hydroxy; and R3 is a heterocylic radical selected from the group consisting of 1-pyrazolyl radicals, 1-triazolyl radicals (including the 1,2,3-;1,2,4-; or 1,3,4-isomers thereof), 4-triazolyl radicals, 1-tetrazolyl radicals or 2-tetrazolyl radicals (including the isomers thereof) and the amino- and alkyl-derivatives of such radicals, including, without limitation, 5-amino-1H-tetrazolyl, 3-amino-4H-1,2,4 triazolyl, 5-amino-1H-1,2,4 triazolyl, 5-amino-2H-tetrazolyl and 5-methyl-1H-tetrazolyl radicals.
In accordance with another aspect, the present invention provides a class of novel intermediates that are useful in preparing the anti-viral agents described herein. These intermediates have the general formula: 
wherein Q represents a reactive group selected from those consisting of 5,5-dimethyl-1,3-dioxan and formyl; R5 is a radical selected from those consisting of hydrogen and hydroxy; R6 is a radical selected from those consisting of hydroxy, alkoxy, aryloxy and aralkoxy and R7 is a radical selected from those consisting of hydrogen, hydroxy, alkoxy, alkoxyalkyl, halogen, perfluoroalkyl, thio, nitro, carboxy, carboxyalkyl, carbalkoxy, carbalkoxyalkyl, carboxamide, carboxamidoalkyl, alkyl, cycloalkyl, alkylthio, alkylsulfinyl, alkylsulfonyl, sulfonamide, amidino, cyano, amino, amido, alkylamino, dialkylamino, alkylaminoalkyl, or alkoxy monosubstituted with a substituent selected from the group consisting of carboxy, amino, alkylamino or dialkylamino.
The present invention also provides new synthetic methods for preparation of the compounds described herein. One method comprises causing a 3-halogen substituted-4-alkoxy-substituted benzaldehyde, in which the aldehyde moiety is protected with a protecting group, to undergo reaction with an alkylated alkali metal to effect a halogen-alkali metal exchange; adding to the reaction mixture an alkyl ester of an R-substituted benzoic acid under conditions yielding a dialkoxy-R-substituted triphenylcarbinol derivative including said protecting group; deprotecting and reducing the dialkoxy-R-substituted triphenylcarbinol derivative to restore the aldehyde functional groups and convert the triphenylcarbinol moiety to a triphenylmethane moiety; dealkylating any alkoxy substituents to hydroxy substituents; and reacting the aldehyde functional groups with an amine-substituted heterocyclic reactant to produce the desired product. The R substituents on the benzoic acid ester are selected from the group consisting of hydrogen, alkoxy, alkoxyalkyl, hydroxy, halogen, perfluoroalkyl, thio, nitro, carboxy, carboxyalkyl, carbalkoxy, carbalkoxyalkyl, carboxamide, carboxamidoalkyl, alkyl, cycloalkyl, alkylthio, alkylsulfinyl, alkylsulfonyl, sulfonamide, amidino, cyano, amino, amido, alkylamino, dialkylamino, alkylaminoalkyl, or alkoxy monosubstituted with a substituent selected from the group consisting of carboxy, amino, alkylamino or dialkylamino.
Another method for preparing compounds of this invention comprises reacting a 4,4xe2x80x2-dihydroxy-3,3xe2x80x2-(4-R-substituted phenyl)methylenebisbenzaldehyde, in which the hydroxy groups are etherified, with the anion of a methyl-substituted heterocyclic reactant to yield a heterocyclic hydroxyalkyl derivative of etherified, R-substituted triphenylmethane as an intermediate product; and subjecting the intermediate product to dehydration and deetherification to produce the desired product.
According to still another aspect, the present invention provides pharmaceutical compositions comprising one or more of the above-described compounds in combination with a pharmaceutically acceptable carrier medium.
In accordance with a further aspect, the present invention provides a method for preventing and treating pneumovirus infection and for preventing and treating diseases associated with pneumovirus infection in living hosts, by administering to a living host susceptible to pneumovirus infection a therapeutically effective amount of a compound of the above structures and/or the isomers and pharmaceutically acceptable salts of said compounds, or pharmaceutical compositions containing same.
The compounds of the invention can be conveniently prepared from known starting materials according to one of the synthetic scheme illustrated below, wherein R and Het are as previously defined. 
Synthetic scheme A involves protection of the aldehyde moiety of a bromobenzaldehyde followed by halogen-metal exchange and reaction of two equivalents of the desired aryl lithium species with an ester group to provide a triaryl methanol. Reduction and regeneration of the aldehyde can be achieved with formic acid. Liberation of the phenolic groups with boron tribromide (or pyridine hydrochloride) and condensation of the aldehyde groups with the appropriate heterocyclic amine provides the compounds of the invention. 
Synthetic scheme B involves the reaction of a bis aldehyde, prepared as described in Scheme A, above, with the anion of a methyl heterocycle generated from n-butyl lithium to give a heterocyclic hydroxyalkyl derivative of an etherified, R-substituted triphenylmethane, as an intermediate product. Dehydration of the intermediate with methane sulfonyl chloride provides the unsaturated compound which is deetherified with boron tribromide to give the desired compound.
The term xe2x80x9calkylxe2x80x9d, as used herein, refers to aliphatic hydrocarbon radicals of one to six carbon atoms in length. Similarly, the term xe2x80x9calkylxe2x80x9d, or any variation thereof, used in combination form to name substituents, such as alkoxy (xe2x80x94O-alkyl), alkylthio (xe2x80x94S-alkyl), alkylamino (xe2x80x94NH-alkyl), alkylsulfonyl (xe2x80x94S(O)2-alkyl), carboxyalkyl (-alkyl-COOH), or the like, also refers to aliphatic hydrocarbon radicals of one to six carbon atoms in length, and preferably of one to four carbon atoms in length.
The designation xe2x80x9cHetxe2x80x9d, as used herein, refers to an unsubstituted or substituted 5-7 membered heterocyclic ring substituent on the compounds of the invention, which substituent contains 1-3 heteroatoms selected from nitrogen, oxygen or sulfur, in which the heterocyclic ring substituent is at least one selected from the group of hydrogen, alkyl, amino, alkylamino or dialkylamino. Representative examples of such heterocyclic rings include, without limitation, those derived from pyrazole, triazole, tetrazole, oxadiazole, thiadiazole, imidazole, oxazole, thiazole, isoxazole, pyridine, pyrimidine, triazine, morpholine, piperidine, piperazine, 1,2,4-diazepine or the like.
The term xe2x80x9camidoxe2x80x9d, as used herein, refers to a radical or substituent of the formula xe2x80x94NRxe2x80x3C(xe2x95x90O)Rxe2x80x2xe2x80x3, wherein Rxe2x80x3 and Rxe2x80x2xe2x80x3 represent hydrogen or alkyl.
The term xe2x80x9ccarboxamidexe2x80x9d, as used herein, refers to a radical or substituent of the formula xe2x80x94C(xe2x95x90O)xe2x80x94NRxe2x80x3Rxe2x80x2xe2x80x3, wherein Rxe2x80x3 and Rxe2x80x2xe2x80x3 are as previously defined.
The term xe2x80x9csulfonamidexe2x80x9d, as used herein, refers to a radical or substituent of the formula xe2x80x94SO2NRxe2x80x3Rxe2x80x2xe2x80x3 or xe2x80x94NRxe2x80x3SO2Rxe2x80x2xe2x80x3, wherein Rxe2x80x3 and Rxe2x80x2xe2x80x3 are as previously defined.
The term xe2x80x9ccarbalkoxyxe2x80x9d, as used herein, refers to a radical or substituent xe2x80x94C(xe2x95x90O)xe2x80x94ORxe2x80x3, wherein Rxe2x80x3 is a previously defined.
Preparation of specific embodiments of anti-pneumovirus compounds within the scope of the invention are exemplified below.
In vitro studies have been performed demonstrating the usefulness of compounds described herein as antiviral agents against pneumoviruses. Antiviral activity was measured on the basis of activity against RSV in a cell culture assay.
All possible isomers of the compounds described herein are within the scope of the present invention. Representative examples of such isomers include, without limitation, cis and trans isomers.
The compounds described herein, their isomers and pharmaceutically acceptable salts exhibit antiviral activity against pneumoviruses and are within the scope of the present invention.
The compounds of the invention can form useful salts with inorganic and organic acids, including, for example, hydrochloric acid, hydrobromic acid, methanesulfonic acid salts, or the like, as well as with inorganic bases, such as sodium or potassium salts.
The pharmaceutically acceptable salts of the compounds of the invention are prepared following procedures which are familiar to those skilled in the art.
The antiviral pharmaceutical compositions of the present invention comprise one or more of the above-described compounds or precursors thereof, as the primary active ingredient in combination with a pharmaceutically acceptable carrier medium and, optionally one or more supplemental active agents.
The composition may be prepared in various forms for administration, including tablets, caplets, pills or dragees, or can be filled in suitable containers, such as capsules, or, in the case of suspensions, filled into bottles. As used herein, xe2x80x9cpharmaceutically acceptable carrier mediumxe2x80x9d includes any and all solvents, diluents, or other liquid vehicle, dispersion or suspension aids, surface active agents, isotonic agents, thickening or emulsifying agents, preservatives, solid binders, lubricants and the like, as suited to the particular dosage form desired. Remington""s Pharmaceutical Sciences, Fifteenth Edition, E. W. Martin (Mack Publishing Co., Easton, Pa., 1975) discloses various carriers used in formulating pharmaceutical compositions and known techniques for the preparation thereof. Except insofar as any conventional carrier medium is incompatible with the antiviral compounds of the invention, such as by producing any undesirable biological effect or otherwise interacting in a deleterious manner with any other component(s) of the pharmaceutical composition, its use is contemplated to be within the scope of this invention.
The compounds of the invention, any precursors thereof and their isomers and pharmaceutically acceptable salts are also useful in treating and preventing pneumovirus infections and diseases when used in combination with supplemental active agents, which may be optionally incorporated into the pharmaceutical composition of the invention, or otherwise administered during a course of therapy. These include, without limitation, interferons, ribavirin, and immunomodulators, immunoglobulins, anti-flammatory agents, antibiotics, anti-virals, anti-infectives, and the like, the combination of which with one or more compounds of the invention offers additive or synergistic therapeutic benefit.
In the pharmaceutical compositions of the invention, the active agent may be present in any therapeutically effective amount, which is typically at least 0.1% and generally not more than 90% by weight, based on the total weight of the composition, including carrier medium and/or supplemental active agent(s), if any. Preferably, the proportion of active agent varies between 1-50% by weight of the composition.
Pharmaceutical organic or inorganic solid or liquid carrier media suitable for enteral or parenteral administration can be used to make up the composition. Gelatine, lactose, starch, magnesium, stearate, talc, vegetable and animal fats and oils, gum, polyalkylene glycol, or other known carriers or excipients for medicaments may all be suitable as carrier media.
Compounds of the invention are usefull in treating and preventing pneumovirus infections (and diseases) in humans, as well as in livestock, and may be used to treat cattle, swine and sheep, or to treat avian species such as turkeys, or for other animals susceptible to pneumovirus infection. Thus, the term xe2x80x9cpatientxe2x80x9d as used herein includes, without limitation, all of the foregoing.
Compounds described herein are also useful in preventing or resolving pneumoviral infections in cell cultures, tissue cultures and organ cultures, as well as other in vitro applications. For example, inclusion of compounds of the invention as a supplement in cell or tissue culture growth media and cell or tissue culture components will prevent pneunoviral infections of cultures not previously infected with pneumoviruses. Compounds described above may also be used to eliminate pneumoviruses from cultures or other materials infected or contaminated with pneumoviruses, after a suitable treatment period, under any number of treatment conditions as determined by the skilled artisan.
The compounds of the invention may be administered using any amount and any route of administration effective for attenuating infectivity of the pneumovirus. Thus, the expression xe2x80x9camount effective to attenuate infectivity of pneumovirusxe2x80x9d, as used herein, refers to a nontoxic but sufficient amount of the antiviral agent to provide the desired treatment of viral infection. The exact amount required will vary from subject to subject, depending on the species, age, and general condition of the subject, the severity of the infection, the particular antiviral agent and its mode of administration, and the like.
The anti-pneumovirus compounds are preferably formulated in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to a physically discrete unit of antiviral agent appropriate for the patient to be treated. Each dosage should contain the quantity of active material calculated to produce the desired therapeutic effect either as such, or in association with the selected pharmaceutical carrier medium. Typically, the antiviral compounds of the invention will be administered in dosage units containing from about 0.1 xcexcg to about 50 mg of the antiviral agent, with a range of about 0.001 mg to about 25 mg being preferred.
The compounds of the invention, including their isomers and pharmaceutically acceptable salts, may be administered as such, or in the form of a precursor from which the active agent can be derived, such as a prodrug. A prodrug is a derivative of a compound described herein, the pharmacologic action of which results from the conversion by chemical or metabolic processes in vivo. Prodrugs of the compounds of the invention may include, but are not limited to mono-, di- or tri-esters of simple or functionalized aliphatic carboxylic acids; esters of carbamic acids (Raxe2x80x94(Oxe2x80x94COxe2x80x94NRbRc)n); esters of amino acids (Raxe2x80x94(Oxe2x80x94COxe2x80x94CH(NH2)Rb)n); esters of unsubstituted or substituted aromatic acids (Raxe2x80x94(Oxe2x80x94COxe2x80x94aryl)n), wherein the aryl ring may be substituted with hydroxy, carboxy, lower alkyl, alkylthio, alkylsulphinyl, alkylsulphonyl, phosphoric acid, amino, alkylamido and halogen groups; esters of derivatized phosphoric acids; (acyloxy)methyl or acyloxy(ethyl)ethers (Raxe2x80x94(Oxe2x80x94CH2xe2x80x94Oxe2x80x94COxe2x80x94Rb)n or Raxe2x80x94(Oxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94COxe2x80x94Rb)n); (alkoxycarbonyloxy)methyl or (alkoxycarbonyloxy)ethyl ethers (Raxe2x80x94(Oxe2x80x94CH2xe2x80x94Oxe2x80x94COxe2x80x94Oxe2x80x94Rb)n); and O-glycosides, wherein Ra is a residue of a compound of the invention, Rb and Rc are aliphatic radicals (C1-C10) and n=1-3. Such prodrugs may be prepared according to procedures well known in the field of medicinal chemistry and pharmaceutical formulation science and are within the scope of the present invention.
The compounds of the invention may be administered orally, parenterally, such as by intramuscular injection, intraperitoneal injection, intravenous infusion or the like, or by inhalation, such as by aerosol, in the form of a solution or a dry powder, or the like, or by intubation, depending on the nature and severity of the infection being treated. The compounds of the invention may be administered orally, parenterally, or by inhalation or intubation at dosage levels of about 106 mg to about 1000 mg/kg, one or more times a day, to obtain the desired therapeutic effect.
The compounds of the invention will typically be administered from 1 to 4 times a day so as to deliver the above-mentioned daily dosage. However, the exact regimen for administration of the compounds and compositions described herein will necessarily be dependent on the needs of the individual host being treated, the type of treatment administered and the judgment of the attending physician, veterinarian or medical specialist.
In view of the inhibitory effect on pneumovirus replication in cell culture produced by the compounds used in the method of the invention, it is anticipated that these compounds will be useful not only for therapeutic treatment of pneumovirus infection, but for pneumovirus prophylaxis, as well. The dosages will be essentially the same, whether for treatment or prophylaxis of pneumovirus infection.
The following examples are provided to describe the invention in further detail. These examples, which set forth the preferred mode presently contemplated for carrying out the invention, are intended to illustrate and not to limit the invention.
Examples 1-14 illustrate the chemical synthesis of representative compounds of the invention.